The fouling of marine hardware, especially the fouling of hulls and propellers, due to the incrustation of barnacles, tube worms and other parasites is a process that has plagued shipowners since the first time man ventured upon the sea. In a large ship, the loss of speed and engine efficiency due to fouling is a major problem and the cause of costly periodic maintenance. After a few months in the water, a ship propulsion system loses from 10 to 20 per cent of its efficiency due to fouling. It has been estimated that 60 per cent of the loss is attributable to the fouling of propeller blades, and 40 per cent to the fouling of the hull. Marine engineers try to promote a smooth and rapid flow of water against the propeller blades for maximum efficiency. To this end, propellers are made of a durable and hard substance such as manganese bronze and the blade surfaces are highly polished. Barnacles and tube worms have the uncanny ability to attach themselves to such hard and polished surfaces by first depositing a speck of glutinous substance which provides a temporary bond, then to anchor themselves more permanently by digging into the surface material.
To this day, the most efficient anti-fouling method has been the use of copper coating and copper paints. As the copper reacts with the seawater, toxic salts are produced which kill the parasitic sea life. The use of copper or other anti-fouling toxic metals has a serious disadvantage, not the least of which is the polluting of anchoring sites by the toxic salts. Furthermore, copper coating or paint tends to react by electrolysis with other metals of the substrate in the salt water environment. This in turn accelerates the corrosion of the supporting hardware.
Various types of toxic and nontoxic coatings have been tried with little success. Teflon coating which maintains a low coefficient of friction and favorize a high rate of flow of the water against the propeller blades to wash away the parasites has shown some promise. However, since ships tend to spend long periods at the dock sites, barnacles find enough time to anchor themselves permanently to the propellers during these idle periods.